Effects of topically applied cinnamic aldehyde, menthol and capsaicin on heat and cool evoked brain potentials in healthy young volunteers

Details

Supervisors

Mouraux, André

Faculty

Faculté des sciences de la motricité

Degree label

Master [120] en sciences de la motricité

Abstract

Objective: By recording contact heat (CHEPs) and cool evoked potentials (CCEPs) after topical application of chemical agonists of TRPM8, TRPA1 or TRPV1 or vehicle, this study aimed to assess the expression of these thermosensitive TRP channels by type II AMH and cool Aδ fibres in healthy young volunteers. Method: 12 healthy young volunteers 5*5 cm surface on the volar forearm was pre-treated with either capsaicin (0.005%), CA (0.5%) or menthol (5%) solution. Vehicle on the other arm. Patch removed after 10’. Each subject attended 3 sessions (1 week between each session) and was treated with each product. 30 hot (60°C) and 30 cool (5°C below baseline) stimulation on each forearm in the pretreated area, slope: 300°C/s, duration: 150 ms, stimulation surface: 115 mm² Verbal rating of intensity (on a 0-10 scale) was asked to the subject after each stimulus. 32 channel EEG recording. Automated single trial analysis. Skin temperature and spontaneous sensation were monitored. Results: CCEP P2 latency was delayed following menthol application. CHEP N2P2 amplitude was affected by the factor vehicle vs product. There is a tendency in absolute values towards a decrease of amplitude following menthol and capsaicin application, however, post-hoc yielded no significant results. Conclusion: Very subtle changes in evoked brain responses were observed following capsaicin and menthol application. However, further studies with larger sample size/ better experimental design are needed.